For typesetting arabic with LaTeX there are arabtex and arabi;
for typesetting arabic with XeLaTeX there are arabxetex and polyglossia;
but how to typeset arabic with LuaLaTeX, since neither of these packages/methods does not work? And there is definitely a way (with very nice results) as demonstrated in "Fonts" papers (PDF) from LuaTeX web page.

Thank you very much for sharing this info.
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Meho R.Mar 14 '12 at 18:18

The definition of \n and so \textarabic is wrong. See implementation of \LRE and \RLE macros in bidi package.
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Simurgh12Apr 25 '12 at 15:21

@Simurgh12 I don't know whether you could really say that they are "wrong". I am not an expert on this but I thought that this solution actually does not use bidi and thus does not use the bidi-commands \LRE and \RLE. But, as I said, I don't know -- it just works perfectly.
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ClintEastwoodMay 5 '12 at 13:56

@ClintEastwood: It does not work perfectly as you claim. For instance, try \n{\verb|\Hello|} with your given code/example above and see what happens. Also try \LRE{\verb|\Hello|} with bidi package in xelatex and see the results for yourself.
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Simurgh12May 6 '12 at 2:40

@Simurgh12: I tried both and got different sorts of error. In fact, a few weeks ago I tried to get bidi to work and failed. Thus, I was happy to receive the solution which I shared. Why don't you just tell us what you'd recommend? Couldn't you just give your answer to the initial question?
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ClintEastwoodMay 7 '12 at 11:00